Three genetics researchers at The Children’s Hospital of Philadelphia are among the co-authors of a large international study that discovered that genes affecting a pregnant mother’s weight, blood sugar and blood pressure also affect the birth weight of her newborn. Being overweight or having higher blood glucose during pregnancy causes a baby to have a higher birth weight. However, if the mother has higher blood pressure, her newborn is likely to be smaller.

The research included over 30,000 healthy women from 18 different studies, and was led by scientists from the Universities of Exeter and Bristol in the U.K. It was published in this week’s Journal of the American Medical Association.

Three CHOP scientists, all from the Center for Applied Genomics, collaborated in this study: Hakon Hakonarson, M.D., Ph.D., the Center’s director; Struan Grant, Ph.D.; and Jonathan P. Bradfield, the Center’s principal analyst on the study. Collaborators from multiple centers in 11 countries, under the Early Growth Genetics Consortium, contributed to the study.

“This study helps to show a cause-and-effect relationship between a mothers’ weight, glucose and blood pressure and her baby’s size,” said Hakonarson. “It also helps to inform public health knowledge.” Grant added, “This work highlights how leveraging modern genetics can help clarify such relationships.” However, said Hakonarson, “Further research is necessary before scientists can issue more specific public health recommendations for managing a healthy pregnancy.”

The study’s overall leaders said that next steps in research include investigating whether the mothers’ influence on their babies’ birth weight has lasting, lifelong effects on those children.